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# How-How Diagram

Quality Tools > Tools of the Trade > 26: How-How Diagram

Once you have discovered why a problem occurs, the matching question that is asked next is ‘How?’. Given the cause of a problem, the requirement then is to find a solution which will permanently fix the cause (just as there are root causes, there are similar critical solutions which properly fix the problem rather than applying a temporary bandage).

## How it works

The How-How Diagram works by repeatedly asking the same question of a problem, breaking down the solution into more and more explicit elements. At each stage, there can be multiple answers to the ‘How’ questions, which results in a hierarchical tree-structure.

Making this tree visible gives several advantages:

§       It allows a group of people to share the mental model of the situation and hence work more harmoniously on it.

§       It allows re-examination of parts of the analysis, so you can change, remove or add to it at any time. This supports the non-linear way in which we tend to think.

§       It allows you to consciously not to follow some paths, digging only into the most likely areas.

Why-How-How Diagram

## How to do it

1. Write the problem on a Post-it Note and place it to the left of a large work area on the wall. A big sheet of brown paper or several flip-chart pages taped together can help. Note that the starting problem of a How-How session may be the key cause as identified by a preceding Why-Why analysis.

2. Ask ‘What are the main sub-areas by which the problem may be solved?’. Write each of these on a Post-it Note and stick them up, well spaced out (to allow lower-level trees to develop) to the right of the problem Post-it Note.

3. Repeat this sequence of breaking down the problem once more, this time simply asking ‘How can I do this?’

4. After this third level, a fourth detailed level would overcrowd the work area, so start to focus by only developing likely-looking causes or solution areas. In each of these, keep asking How until you have a root cause or a complete solution.

5. When you have completed the analysis, discuss and identify the key solution to implement.

Next time: The Humble Check Sheet

This article first appeared in Quality World, the journal of the Institute for Quality Assurance

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